// ===================================================================
// Author: Matt Kruse <matt@mattkruse.com>
// WWW: http://www.mattkruse.com/
//
// NOTICE: You may use this code for any purpose, commercial or
// private, without any further permission from the author. You may
// remove this notice from your final code if you wish, however it is
// appreciated by the author if at least my web site address is kept.
//
// You may *NOT* re-distribute this code in any way except through its
// use. That means, you can include it in your product, or your web
// site, or any other form where the code is actually being used. You
// may not put the plain javascript up on your site for download or
// include it in your javascript libraries for download. 
// If you wish to share this code with others, please just point them
// to the URL instead.
// Please DO NOT link directly to my .js files from your site. Copy
// the files to your server and use them there. Thank you.
// ===================================================================

// HISTORY
// ------------------------------------------------------------------
// Feb 15, 2005: Documentation Fix
// March 31, 2004: First release
/* 

DESCRIPTION: This library allows you to easily create select boxes whose
contents depend on the value in a parent select box. It supports default
options, preselected options, single or multiple-select lists, multiple
form fields referencing the same list structure, form resetting, and most
importantly, it's backwards-compatible way back to Netscape 4!

COMPATABILITY: Netscape 4+, IE, Opera >5 (O5 didn't support new Option()),
and should work on all other newer browsers.

USAGE:

    // Create a new object, passing in the fields that make up the dynamic set 
    // of lists.
var dol = new DynamicOptionList("Field1","Child1","Child2");
    
    // Or, you can create it empty, and pass in sets of select objects later
var dol = new DynamicOptionList();
dol.addDependentFields("Field1","Child1","Child2");

    // Once you have the list object defined, you can additional sets of dependent
    // fields, too. These sets will act as separate groups of related fields, but
    // will all use the same options and data.
dol.addDependentOptions("Field1","Child2-1","Child2-2");

    // By default, the script will automatically find the form where your select
    // objects exist. But you can explicitly set it if you wish, either by form 
    // name or index.
dol.setFormName("MyForm");
dol.setFormIndex(1);

    // Now define the options that will exist in sub-lists. This is done in a 
    // very logical way - you say for an option in the parent, populate the child
    // with specific options. When selecting which parent option you're dealing
    // with, you can either select by its value or its display text. This command
    // says, for an option in the parent list that has value="Value1", if it is
    // selected then populate the child list with the given sub-options.
dol.forValue("Value1").addOptions("Suboption1","Suboption2","Suboption3");

    // And you can also say, for an option in the parent list that has display
    // text of "Text1", if it is selected then populate the child list with the
    // given sub-options.
dol.forText("Text1").addOptions("Suboption1","Suboption2","Suboption3");

    // For multi-level lists, you just continue the chain...
    // This says, if an option with value "Value1" is selected in the first list,
    // then an option with values "Value2" is selected in the second list, populate
    // the third list with these options.
dol.forValue("Value1").forValue("Value2").addOptions("1","2","3");

    // If the options you want to add should have different values and dislplay
    // text, you can do that
dol.forValue("Value1").addOptionsTextValue("Text2","Value2");

    // When an option is selected from the first list, and the options in the 
    // second list are populated, you may want to have one of the options in the
    // child list be selected by default.
dol.forValue("Value1").setDefaultOptions("MyValue");

    // When the page first loads, you may set the values of the dependent select
    // lists to be selected by default. For example, when a user is editing an
    // existing record where they've already selected from the parent/child
    // relationships. This is different from the default option in that this
    // value is only selected when the page LOADS. If the user changes selections,
    // this will be lost.
dol.forField("Field1").setValues("MyPreselectedValue");

    // By default, if there are is no option which should be selected in the child
    // list, the code will automatically select the first option in the list. If 
    // you want it to instead set selectedIndex = -1 (nothing selected - works in
    // most browsers but not all) than you can tell it to do that instead
dol.selectFirstOption = false;

// MODIFYING THE HTML
// If you are supporting Netscape 4.x browsers, you will need to insert a call to
// the library to populate options. This is because Netscape4 will not expand the
// size of the select box as new options are added, so you have to "pad" the list
// with blank options in order for it to work right. 
// This is the ONLY change you should need to make to your HTML. To do this, just
// add a javascript block between your <select> </select> tags like this:

<select name="list1"><script>dol.printOptions("list1")</script></select>

// You only need to pass it the name of the select options that it should print
// options for.


NOTES:
 - There seems to be an issue with Netscape6, if you hit Reload on the page. It
   doesn't happen every time, and I can't figure out why it happens at all.

 - If your select objects have onChange handlers in them, you'll need to manually
   add a call to the DynamicOptionList code to trigger the population of the child
   list. For example,
   
   <select onChange="yourfunction(); dol.change(this)">
 
*/ 
// Global objects to keep track of DynamicOptionList objects created on the page
var dynamicOptionListCount=0;
var dynamicOptionListObjects = new Array();

// Init call to setup lists after page load. One call to this function sets up all lists.
function initDynamicOptionLists() {
    // init each DynamicOptionList object
    for (var i=0; i<dynamicOptionListObjects.length; i++) {
        var dol = dynamicOptionListObjects[i];

        // Find the form associated with this list
        if (dol.formName!=null) { 
            dol.form = document.forms[dol.formName];
        }
        else if (dol.formIndex!=null) {
            dol.form = document.forms[dol.formIndex];
        }
        else {
            // Form wasn't set manually, so go find it!
            // Search for the first form element name in the lists
            var name = dol.fieldNames[0][0];
            for (var f=0; f<document.forms.length; f++) {
                if (typeof(document.forms[f][name])!="undefined") {
                    dol.form = document.forms[f];
                    break;
                }
            }
            if (dol.form==null) {
                alert("ERROR: Couldn't find form element "+name+" in any form on the page! Init aborted"); return;
            }
        }

        // Form is found, now set the onchange attributes of each dependent select box
        for (var j=0; j<dol.fieldNames.length; j++) {
            // For each set of field names...
            for (var k=0; k<dol.fieldNames[j].length-1; k++) {
                // For each field in the set...
                var selObj = dol.form[dol.fieldNames[j][k]];
                if (typeof(selObj)=="undefined") { alert("Select box named "+dol.fieldNames[j][k]+" could not be found in the form. Init aborted"); return; }
                // Map the HTML options in the first select into the options we created
                if (k==0) {
                    if (selObj.options!=null) {
                        for (l=0; l<selObj.options.length; l++) {
                            var sopt = selObj.options[l];
                            var m = dol.findMatchingOptionInArray(dol.options,sopt.text,sopt.value,false);
                            if (m!=null) {
                                var reselectForNN6 = sopt.selected;
                                var m2 = new Option(sopt.text, sopt.value, sopt.defaultSelected, sopt.selected);
                                m2.selected = sopt.selected; // For some reason I need to do this to make NN4 happy
                                m2.defaultSelected = sopt.defaultSelected;
                                m2.DOLOption = m;
                                selObj.options[l] = m2;
                                selObj.options[l].selected = reselectForNN6; // Reselect this option for NN6 to be happy. Yuck.
                            }
                        }
                    }
                }
                if (selObj.onchange==null) {
                    // We only modify the onChange attribute if it's empty! Otherwise do it yourself in your source!
                    selObj.onchange = new Function("dynamicOptionListObjects["+dol.index+"].change(this)");
                }
            }
        }
    }
    // Set the preselectd options on page load 
    resetDynamicOptionLists();
}

// This function populates lists with the preselected values. 
// It's pulled out into a separate function so it can be hooked into a 'reset' button on a form
// Optionally passed a form object which should be the only form reset
function resetDynamicOptionLists(theform) {
    // reset each DynamicOptionList object
    for (var i=0; i<dynamicOptionListObjects.length; i++) {
        var dol = dynamicOptionListObjects[i];
        if (typeof(theform)=="undefined" || theform==null || theform==dol.form) {
            for (var j=0; j<dol.fieldNames.length; j++) {
                dol.change(dol.form[dol.fieldNames[j][0]],true); // Second argument says to use preselected values rather than default values
            }
        }
    }
}

// An object to represent an Option() but just for data-holding
function DOLOption(text,value,defaultSelected,selected) {
    this.text = text;
    this.value = value;
    this.defaultSelected = defaultSelected;
    this.selected = selected;
    this.options = new Array(); // To hold sub-options
    return this;
}

// DynamicOptionList CONSTRUCTOR
function DynamicOptionList() {
    this.form = null;// The form this list belongs to
    this.options = new Array();// Holds the options of dependent lists
    this.longestString = new Array();// Longest string that is currently a potential option (for Netscape)
    this.numberOfOptions = new Array();// The total number of options that might be displayed, to build dummy options (for Netscape)
    this.currentNode = null;// The current node that has been selected with forValue() or forText()
    this.currentField = null;// The current field that is selected to be used for setValue()
    this.currentNodeDepth = 0;// How far down the tree the currentNode is
    this.fieldNames = new Array();// Lists of dependent fields which use this object
    this.formIndex = null;// The index of the form to associate with this list
    this.formName = null;// The name of the form to associate with this list
    this.fieldListIndexes = new Object();// Hold the field lists index where fields exist
    this.fieldIndexes = new Object();// Hold the index within the list where fields exist
    this.selectFirstOption = true;// Whether or not to select the first option by default if no options are default or preselected, otherwise set the selectedIndex = -1
    this.numberOfOptions = new Array();// Store the max number of options for a given option list
    this.longestString = new Array();// Store the longest possible string 
    this.values = new Object(); // Will hold the preselected values for fields, by field name
    
    // Method mappings
    this.forValue = DOL_forValue;
    this.forText = DOL_forText;
    this.forField = DOL_forField;
    this.forX = DOL_forX;
    this.addOptions = DOL_addOptions;
    this.addOptionsTextValue = DOL_addOptionsTextValue;
    this.setDefaultOptions = DOL_setDefaultOptions;
    this.setValues = DOL_setValues;
    this.setValue = DOL_setValues;
    this.setFormIndex = DOL_setFormIndex;
    this.setFormName = DOL_setFormName;
    this.printOptions = DOL_printOptions;
    this.addDependentFields = DOL_addDependentFields;
    this.change = DOL_change;
    this.child = DOL_child;
    this.selectChildOptions = DOL_selectChildOptions;
    this.populateChild = DOL_populateChild;
    this.change = DOL_change;
    this.addNewOptionToList = DOL_addNewOptionToList;
    this.findMatchingOptionInArray = DOL_findMatchingOptionInArray;

    // Optionally pass in the dependent field names
    if (arguments.length > 0) {
        // Process arguments and add dependency groups
        for (var i=0; i<arguments.length; i++) {
            this.fieldListIndexes[arguments[i].toString()] = this.fieldNames.length;
            this.fieldIndexes[arguments[i].toString()] = i;
        }
        this.fieldNames[this.fieldNames.length] = arguments;
    }
    
    // Add this object to the global array of dynamicoptionlist objects
    this.index = window.dynamicOptionListCount++;
    window["dynamicOptionListObjects"][this.index] = this;
}

// Given an array of Option objects, search for an existing option that matches value, text, or both
function DOL_findMatchingOptionInArray(a,text,value,exactMatchRequired) {
    if (a==null || typeof(a)=="undefined") { return null; }
    var value_match = null; // Whether or not a value has been matched
    var text_match = null; // Whether or not a text has been matched
    for (var i=0; i<a.length; i++) {
        var opt = a[i];
        // If both value and text match, return it right away
        if (opt.value==value && opt.text==text) { return opt; }
        if (!exactMatchRequired) {
            // If value matches, store it until we complete scanning the list
            if (value_match==null && value!=null && opt.value==value) {
                value_match = opt;
            }
            // If text matches, store it for later
            if (text_match==null && text!=null && opt.text==text) {
                text_match = opt;
            }
        }
    }
    return (value_match!=null)?value_match:text_match;
}

// Util function used by forValue and forText
function DOL_forX(s,type) {
    if (this.currentNode==null) { this.currentNodeDepth=0; }
    var useNode = (this.currentNode==null)?this:this.currentNode;
    var o = this.findMatchingOptionInArray(useNode["options"],(type=="text")?s:null,(type=="value")?s:null,false);
    if (o==null) {
        o = new DOLOption(null,null,false,false);
        o[type] = s;
        useNode.options[useNode.options.length] = o;
    }
    this.currentNode = o;
    this.currentNodeDepth++;
    return this;
}

// Set the portion of the list structure that is to be used by a later operation like addOptions
function DOL_forValue(s) { return this.forX(s,"value"); }

// Set the portion of the list structure that is to be used by a later operation like addOptions
function DOL_forText(s) { return this.forX(s,"text"); }

// Set the field to be used for setValue() calls
function DOL_forField(f) { this.currentField = f; return this; }

// Create and add an option to a list, avoiding duplicates
function DOL_addNewOptionToList(a, text, value, defaultSelected) {
    var o = new DOLOption(text,value,defaultSelected,false);
    // Add the option to the array
    if (a==null) { a = new Array(); }
    for (var i=0; i<a.length; i++) {
        if (a[i].text==o.text && a[i].value==o.value) {
            if (o.selected) { 
                a[i].selected=true;
            }
            if (o.defaultSelected) {
                a[i].defaultSelected = true;
            }
            return a;
        }
    }
    a[a.length] = o;
}

// Add sub-options to the currently-selected node, with the same text and value for each option
function DOL_addOptions() {
    if (this.currentNode==null) { this.currentNode = this; }
    if (this.currentNode["options"] == null) { this.currentNode["options"] = new Array(); }
    for (var i=0; i<arguments.length; i++) {
        var text = arguments[i];
        this.addNewOptionToList(this.currentNode.options,text,text,false);
        if (typeof(this.numberOfOptions[this.currentNodeDepth])=="undefined") {
            this.numberOfOptions[this.currentNodeDepth]=0;
        }
        if (this.currentNode.options.length > this.numberOfOptions[this.currentNodeDepth]) {
            this.numberOfOptions[this.currentNodeDepth] = this.currentNode.options.length;
        }
        if (typeof(this.longestString[this.currentNodeDepth])=="undefined" || (text.length > this.longestString[this.currentNodeDepth].length)) {
            this.longestString[this.currentNodeDepth] = text;
        }
    }
    this.currentNode = null;
    this.currentNodeDepth = 0;

//    alert('ok');
}

// Add sub-options to the currently-selected node, specifying separate text and values for each option
function DOL_addOptionsTextValue() {
    if (this.currentNode==null) { this.currentNode = this; }
    if (this.currentNode["options"] == null) { this.currentNode["options"] = new Array(); }
    for (var i=0; i<arguments.length; i++) {
        var text = arguments[i++];
        var value = arguments[i];
        this.addNewOptionToList(this.currentNode.options,text,value,false);
        if (typeof(this.numberOfOptions[this.currentNodeDepth])=="undefined") {
            this.numberOfOptions[this.currentNodeDepth]=0;
        }
        if (this.currentNode.options.length > this.numberOfOptions[this.currentNodeDepth]) {
            this.numberOfOptions[this.currentNodeDepth] = this.currentNode.options.length;
        }
        if (typeof(this.longestString[this.currentNodeDepth])=="undefined" || (text.length > this.longestString[this.currentNodeDepth].length)) {
            this.longestString[this.currentNodeDepth] = text;
        }
    }
    this.currentNode = null;
    this.currentNodeDepth = 0;
}

// Find the first dependent list of a select box
// If it's the last list in a chain, return null because there are no children
function DOL_child(obj) {
    var listIndex = this.fieldListIndexes[obj.name];
    var index = this.fieldIndexes[obj.name];
    if (index < (this.fieldNames[listIndex].length-1)) {
        return this.form[this.fieldNames[listIndex][index+1]];
    }
    return null;
}

// Set the options which should be selected by default for a certain value in the parent
function DOL_setDefaultOptions() {
    if (this.currentNode==null) { this.currentNode = this; }
    for (var i=0; i<arguments.length; i++) {
        var o = this.findMatchingOptionInArray(this.currentNode.options,null,arguments[i],false);
        if (o!=null) {
            o.defaultSelected = true;
        }
    }
    this.currentNode = null;
}

// Set the options which should be selected when the page loads. This is different than the default value and ONLY applies when the page LOADS
function DOL_setValues() {
    if (this.currentField==null) { 
        alert("Can't call setValues() without using forField() first!");
        return;
    }
    if (typeof(this.values[this.currentField])=="undefined") {
        this.values[this.currentField] = new Object();
    }
    for (var i=0; i<arguments.length; i++) {
        this.values[this.currentField][arguments[i]] = true;
    }
    this.currentField = null;
}

// Manually set the form for the object using an index
function DOL_setFormIndex(i) {
    this.formIndex = i;
}

// Manually set the form for the object using a form name
function DOL_setFormName(n) {
    this.formName = n;
}

// Print blank <option> objects for Netscape4, since it refuses to grow or shrink select boxes for new options
function DOL_printOptions(name) {
    // Only need to write out "dummy" options for Netscape4
    if ((navigator.appName == 'Netscape') && (parseInt(navigator.appVersion) <= 4))
    {
      var index = this.fieldIndexes[name];
      var ret = "";

      if (typeof(this.numberOfOptions[index])!="undefined")
      {
        for (var i=0; i<this.numberOfOptions[index]; i++)
        {
          ret += "<OPTION>";
        }
      }
      ret += "<OPTION>";
      if (typeof(this.longestString[index])!="undefined")
      {
        for (var i=0; i<this.longestString[index].length; i++)
        {
          ret += "_";
        }
      }
      document.writeln(ret);
    }
}

// Add a list of field names which use this option-mapping object.
// A single mapping object may be used by multiple sets of fields
function DOL_addDependentFields() {
    for (var i=0; i<arguments.length; i++) {
        this.fieldListIndexes[arguments[i].toString()] = this.fieldNames.length;
        this.fieldIndexes[arguments[i].toString()] = i;
    }
    this.fieldNames[this.fieldNames.length] = arguments;
}

// Called when a parent select box is changed. It populates its direct child, then calls change on the child object to continue the population.
function DOL_change(obj, usePreselected) {
    if (usePreselected==null || typeof(usePreselected)=="undefined") { usePreselected = false; }
    var changedListIndex = this.fieldListIndexes[obj.name];
    var changedIndex = this.fieldIndexes[obj.name];
    var child = this.child(obj);
    if (child == null) { return; } // No child, no need to continue
    if (obj.type == "select-one") {
        // Treat single-select differently so we don't have to scan the entire select list, which could potentially speed things up
        if (child.options!=null) {
            child.options.length=0; // Erase all the options from the child so we can re-populate
        }
        if (obj.options!=null && obj.options.length>0 && obj.selectedIndex>=0) {
            var o = obj.options[obj.selectedIndex];
            this.populateChild(o.DOLOption,child,usePreselected);
            this.selectChildOptions(child,usePreselected);
        }
    }
    else if (obj.type == "select-multiple") {
        // For each selected value in the parent, find the options to fill in for this list
        // Loop through the child list and keep track of options that are currently selected
        var currentlySelectedOptions = new Array();
        if (!usePreselected) {
            for (var i=0; i<child.options.length; i++) {
                var co = child.options[i];
                if (co.selected) {
                    this.addNewOptionToList(currentlySelectedOptions, co.text, co.value, co.defaultSelected);
                }
            }
        }
        child.options.length=0;
        if (obj.options!=null) {
            var obj_o = obj.options;
            // For each selected option in the parent...
            for (var i=0; i<obj_o.length; i++) {
                if (obj_o[i].selected) {
                    // if option is selected, add its children to the list
                    this.populateChild(obj_o[i].DOLOption,child,usePreselected);
                }
            }
            // Now go through and re-select any options which were selected before
            var atLeastOneSelected = false;
            if (!usePreselected) {
                for (var i=0; i<child.options.length; i++) {
                    var m = this.findMatchingOptionInArray(currentlySelectedOptions,child.options[i].text,child.options[i].value,true);
                    if (m!=null) {
                        child.options[i].selected = true;
                        atLeastOneSelected = true;
                    }
                }
            }
            if (!atLeastOneSelected) {  
                this.selectChildOptions(child,usePreselected);
            }
        }
    }
    // Change all the way down the chain
    this.change(child,usePreselected);
}
function DOL_populateChild(dolOption,childSelectObj,usePreselected) {
    // If this opton has sub-options, populate the child list with them
    if (dolOption!=null && dolOption.options!=null) {
        for (var j=0; j<dolOption.options.length; j++) {
            var srcOpt = dolOption.options[j];
            if (childSelectObj.options==null) { childSelectObj.options = new Array(); }
            // Put option into select list
            var duplicate = false;
            var preSelectedExists = false;
            for (var k=0; k<childSelectObj.options.length; k++) {
                var csi = childSelectObj.options[k];
                if (csi.text==srcOpt.text && csi.value==srcOpt.value) {
                    duplicate = true;
                    break;
                }
            }
            if (!duplicate) {
                var newopt = new Option(srcOpt.text, srcOpt.value, false, false);
                newopt.selected = false; // Again, we have to do these two statements for NN4 to work
                newopt.defaultSelected = false;
                newopt.DOLOption = srcOpt;
                childSelectObj.options[childSelectObj.options.length] = newopt;
            }
        }
    }
}

// Once a child select is populated, go back over it to select options which should be selected
function DOL_selectChildOptions(obj,usePreselected) {
    // Look to see if any options are preselected=true. If so, then set then selected if usePreselected=true, otherwise set defaults
    var values = this.values[obj.name];
    var preselectedExists = false;
    if (usePreselected && values!=null && typeof(values)!="undefined") {
        for (var i=0; i<obj.options.length; i++) {
            var v = obj.options[i].value;
            if (v!=null && values[v]!=null && typeof(values[v])!="undefined") {
                preselectedExists = true;
                break;
            }
        }
    }
    // Go back over all the options to do the selection
    var atLeastOneSelected = false;
    for (var i=0; i<obj.options.length; i++) {
        var o = obj.options[i];
        if (preselectedExists && o.value!=null && values[o.value]!=null && typeof(values[o.value])!="undefined") {
            o.selected = true;
            atLeastOneSelected = true;
        }
        else if (!preselectedExists && o.DOLOption!=null && o.DOLOption.defaultSelected) {
            o.selected = true;
            atLeastOneSelected = true;
        }
        else {
            o.selected = false;
        }
    }
    // If nothing else was selected, select the first one by default
    if (this.selectFirstOption && !atLeastOneSelected && obj.options.length>0) {
        obj.options[0].selected = true;
    }
    else if (!atLeastOneSelected &&  obj.type=="select-one") {
        obj.selectedIndex = -1;
    }
}